In this paper we report new data on the ascending and descending behavioural patterns of a spiral staircase by 12 toddlers in a special setting. At the beginning of the study they were aged from 17 to 21 months. Two groups of 6 were formed: for one the configuration of the first step was triangular; for the other it was quadrangular. The same groups were followed up between 23 and 27 months in the same conditions and with the same protocol except the configuration of the first step was reversed from one group to the other. We found that: (1) from the age range of 17 to 21 months, the toddlers of both groups used significantly more often the right foot when they attacked the first step, without decrease of their pace and stopping; (2) the configuration of the first step significantly influenced the choice of the attacking foot at the beginning of ascents and the end of descents; (3) the behaviours at the end of ascents and the beginning of descents appeared to be significantly influenced by the configuration of the top part of the staircase and that of the first step; (4) between 23 and 27 months, the role of the developmental factors was especially obvious at the beginning of ascents and the end of descents; (5) the behaviours at the end of ascents and the beginning of descents appeared to be linked to a combination of the developmental factors, the configuration of the top part of the staircase, the individual experiences at the beginning of ascents, and the individual experiences throughout the first part of the study.